Diaphragm - Definition, Function, Muscle & Anatomy | Kenhub

Summary

This video explores the diaphragm, a crucial skeletal muscle in the human body responsible for respiration. The diaphragm separates the thoracic and abdominal cavities and has key openings allowing structures like the aorta and esophagus to pass through. It plays a vital role in breathing by contracting during inhalation and relaxing during exhalation. The video also covers the neurovascular supply, including the phrenic nerves that innervate it. Finally, the script touches on the causes and treatments of hiccups, explaining that while most cases are temporary, persistent hiccups may require medical attention.

Takeaways

• 😀 Hiccups are involuntary spasms of the diaphragm, a muscle crucial for breathing.
• 😀 The diaphragm is a domed sheet of skeletal muscle that separates the thoracic and abdominal cavities.
• 😀 The diaphragm attaches to the xiphoid process, ribs 7-12, and lumbar vertebrae.
• 😀 The muscle fibers of the diaphragm converge at the central tendon, which is vital for its function.
• 😀 The left and right crura of the diaphragm arise from the lumbar vertebrae (L1–L3) and help support its structure.
• 😀 The diaphragm has three major openings: the aortic hiatus (T12), esophageal hiatus (T10), and caval hiatus (T8).
• 😀 The aortic hiatus transmits the aorta, azygos vein, hemiazygos vein, and thoracic duct.
• 😀 The diaphragm's primary function is to assist in breathing by contracting during inspiration and relaxing during expiration.
• 😀 The diaphragm receives blood from the inferior phrenic arteries and venous drainage from the inferior phrenic veins.
• 😀 The diaphragm is innervated by the phrenic nerves (C3–C5), which can be remembered by the rhyme 'C3, 4, and 5 keep the diaphragm alive!'
• 😀 Hiccups can be triggered by stress, spicy food, or abdominal surgery and may last for minutes, days, or even months.
• 😀 Remedies for hiccups include holding your breath, sucking on peppermint, breathing into a paper bag, and in extreme cases, seeing a doctor for medication.

Q & A

What are hiccups and how are they caused?

Hiccups are involuntary spasms of the diaphragm, the muscle that separates the thoracic and abdominal cavities. These spasms cause the vocal cords to close suddenly, producing the characteristic 'hic' sound.

What is the diaphragm and where is it located?

The diaphragm is a domed sheet of skeletal muscle located in the trunk of the body. It separates the thoracic cavity (which houses the heart and lungs) from the abdominal cavity (which contains the stomach, liver, and intestines).

What are the main attachments of the diaphragm?

The diaphragm has three major attachments: the xiphoid process anteriorly, the costal cartilages of ribs 7-10 and ribs 11-12 laterally, and the lumbar vertebrae and arcuate ligaments posteriorly.

What is the central tendon of the diaphragm?

The central tendon of the diaphragm is the central attachment point where the muscle fibers converge. This tendon plays a key role in the diaphragm's function during breathing.

What are the crura of the diaphragm and what is their function?

The crura of the diaphragm are tendinous structures that arise from the vertebrae. The left crus originates from L1 and L2, and the right crus arises from L1 to L3. These structures help anchor the diaphragm to the lumbar vertebrae.

What are the major openings in the diaphragm and what structures pass through them?

The diaphragm has three major openings: the aortic hiatus (transmits the aorta, azygos vein, hemiazygos vein, and thoracic duct), the esophageal hiatus (transmits the esophagus, vagus nerves, and esophageal arteries), and the caval hiatus (transmits the inferior vena cava and the terminal branches of the right phrenic nerve).

How does the diaphragm contribute to respiration?

The diaphragm is the primary muscle of respiration. During inspiration, it contracts and flattens, increasing the volume of the thoracic cavity and allowing the lungs to expand. During expiration, the diaphragm relaxes and returns to its dome-like shape, reducing the thoracic cavity volume and expelling air from the lungs.

What is the neurovascular supply of the diaphragm?

The diaphragm receives arterial supply mainly from the left and right inferior phrenic arteries. Venous drainage is carried out by the inferior phrenic veins. The diaphragm's motor innervation comes from the left and right phrenic nerves, which contain fibers from spinal roots C3, C4, and C5.

What is the mnemonic for remembering the phrenic nerve roots?

The mnemonic to remember the phrenic nerve roots is 'C3, 4, and 5 keep the diaphragm alive!' This highlights the importance of spinal roots C3 to C5 for diaphragm function.

What are some common triggers for hiccups?

Common triggers for hiccups include abdominal surgery, spicy food, and stress. Hiccups often disappear on their own after a few minutes, but in some cases, they can last much longer.